The present invention relates to a photocurable resin composition. More particularly, the present invention relates to a photocurable resin composition useful for forming optical parts, for example, a lens for lens sheets, such as a prism lens sheet used for a backlight of a liquid crystal display and a Fresnel lens sheet or a lenticular lens sheet used for a screen of a projection TV, or a backlight using such sheets.
Lenses such as a Fresnel lens and a lenticular lens have been manufactured by a press method or a cast method. These methods require a long period of time for manufacturing a lens, thereby resulting in poor productivity. In order to solve this problem, a method of manufacturing a lens using a UV-curable resin has been attempted in recent years. Such a method comprises pouring a UV-curable resin composition between a mold having a lens shape and a transparent resin substrate, and curing the composition by irradiating with ultraviolet rays from the side of the substrate to manufacture the lens in a short period of time. Accompanied by the development of thinner and larger projection TVs or video projectors, resins for forming a lens provided with various lens properties such as a higher refractive index and mechanical properties have been proposed and examined. For example, Japanese Patent Application Laid-open No. 2554363/1993 discloses a UV-curable resin composition for a translucent screen which comprises (A) a urethane (meth)acrylate produced by reacting (a) a diol compound produced by reacting bisphenol A with ethylene oxide and the like, (b) a diol compound with a molecular weight of 200 or less, (c) an organic polyisocyanate, and (d) a (meth)acrylate containing a hydroxyl group, (B) a compound containing an ethylenically unsaturated group other than the component (A), and (C) a photoinitiator.
However, conventional UV curable resin compositions could not produce a cured product which satisfies the required lens properties such as adhesion to substrates, abrasion resistance, and restorability of the shape.